Dual idler phonograph drive



Nov. 21, 1950 Filed Jan. 29, 1944 J. J. HOEHN ET AL DUAL IDLERPHONOGRAPH DRIVE 2 Sheets-Sheet 1 (Ittorneg Nov. 2l, 1950 J. J. Hor-:HNErAL DUAL. IDLER PHoNoGRAPH DRIVE 2 Sheets-Sheet 2 Filed Jan. 29., 1944attorney Patented Nov. 21, 1950 DUAL IDLER PHONOGRAPH DRIVE John J.Hoehn and Arthur G. Zimmerman, In-

dianapolis, Ind., assignors to Radio Corporation of America, acorporation of Delaware Original application July 31, 1940, Serial No.348,860. Divided and this application January 29, 1944, Serial No.520,152

(Cl. 'i4-190) Claims. 1

This invention relates to phonographic apparatus of the type adapted torecord sound upon a blank disc ior immediate play-back, and moreparticularly to the turntable driving mechanism thereof, the presentinvention being in the nature of an improvement over those disclosed andclaimed in the Brady and Weathers Patent No. 2,260,289 and the HoehnPatent No. 2,260,319, and the present application being a division ofour copending application Serial No. 348,860, filed July 31, 1940, nowPatent No. 2,359,682, granted June 6, 1945 and assigned to RadioCorporation of America.

In the aforesaid Brady and Weathers patent, there is disclosed aphonograph turntable driving mechanism comprising a driving motor theshaft of which is formed with two pulleys or driving surfaces ofdifferent diameters employed Jfor driving the turntable at one oranother of two speeds by means of an interposed friction idler. Thisdriving mechanism constitutes a part of a phonographic apparatus whichmay be used either for recording sound on a blank disc or playing backthe recorded disc. While satisfactory in many respects, this driving.mechanism is subject to certain inherent limitations which are overcomeby the driving mechanism shown in the Hoehn patent, identified above.According tothe latter, the same type of driving motor with steppedpulley is employed as is disclosed in the Brady and Weathers patent, butinstead of using merely one idler, two friction idlers are employedbetween the driving motor shaft and the turntable. With respect to themotor shaft, the second friction wheel employed by Hoehn is arrangedsymmetrically opposite to the single friction wheel shown by Brady andWeathers. In this way, the transmitted load is divided between the twofriction wheels or idler pulleys. A single control lever which is commonto both of the friction idler supporting arms is arranged to operatesaid arms in order t0 either move them away from or move them intotorque transmitting position.

While the Hoehn arrangement offers certain distinct advantages yoverthat proposed by Brady and Weathers, it has been found, in some cases,that inaccuracies in the driving shaft of the single motor employed andslight irregularities in motor speed may be transmitted to theturntable, since both friction idlers operate from the same motor.Moreover, in arrangements .such as shown in both of the rabove identiedpatents, when the motors are shut-off and the friction idlers aresimultaneously removed v:from

2 engagement with the flange on the turntable eriphery, the turntablecontinues to coast awhile and thus some of the record area is caused tobe used up needlessly.

The primary object or our present invention is to provide an improvedphonograph turntable drive which will not be subject to theaforementioned limitations.

More particularly, it is an object of our present invention to providean improved turntable driving mechanism as aforesaid by means of which amore constant speed of the turntable can be achieved than was possibleheretofore.

Another object of our present invention is to provide an improvedturntable driving mechanism of the type set forth above wherein theturntable may not only be driven very constantly or uniformly at any oneof the plurality of different speeds, but wherein the turntable can bebrought to a quick stop when the motor power is disconnected therefrom.

Still another object of our present invention is to provide an improvedphonograph turntable driving mechanism employing a pair of discretemotors so arranged that the failure of either one of them will notrender the driving mech anism inoperative.

It is also an object of our present invention to provide an improvedturntable driving mechansm as above set forth which is relatively simplein construction and highly efficient in use.

In accordance with our present invention, we

' employ two separate or discrete driving motors spaced somewhatciroumferentially around the turntable and each provided with a pair ofstepped pulleys on its driving shaft arranged to drive the turntable atone or another of two different speeds. Coupling to the turntable isattained through a pair of discrete, floatinglymounted, friction idlers,each associated with a separate one of the motors. In elect, therefore,the turntable is driven at two circumferentially spaced points on theperiphery thereof by two motors which are connected in parallel relationto a common power source. Thus, the failure of one motor still permitsthe second motor to drive the turntable.

rihe chief advantage in employing two motors as above described is thatany slight irregularities that may exist in the drive provided by onewill be overcome by the uniform drive of the other, since it is mostunlikely that both motors will be subject to the same kind ofirregularities at the same points. Consequently, a more uniform drive isprovided for the turntable than when a single motor is employed,regardless of whether a single friction idler or a pair of frictionidlers may cooperate therewith to transmit torque from the single motorto the turntable, as in the above identied patents.

In the arrangement of our present invention, a common control arm isemployed for simultaneously coupling and uncoupling the two idler wheelsto their respective motors and to the turntable. rFhis common controlalso operates a brake device associated with the turntable, thearrangement being such that when the friction idlers are disconnectedfrom their respective motors, the brake is immediately applied to theturntable to stop rotation thereof substantially instantaneously.

The novel features that we consider characteristic of our invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description of one embodiment thereof whenread in connection with the accompanying drawings, in which Figure l isa top plan view of a recording apparatus according to our presentinvention, and

Figure 2 is an enlarged side elevation of the turntable drivingmechanism.

Referring more particularly to the drawings. wherein similar referencecharacters designate corresponding parts throughout, there is shown amotor board l carrying a frame member 2 provided with bushing 3 in whichis journalled a turntable shaft terminating in a tapered spindle 5 onwhich is m unted a turntable the turntable constituting a supportingmeans for a record disc or blank R. The turntable S is driven from apair of motors l, each of which includes a motor shaft formed with arelatively small diameter 'Ia at its upper extremity and a relativelylarge iameter lb immediately below the portion la. ln each case, themotor may be coupled to the periphery of the turntable E by means of c.rubber tired idler 8 which is iioatingly carried on an arri"- 9, eacharm 9 being pivotally mounted on a lever It! which, in turn, is pivotedon a post EE, a coil spring i2 around each of the posts il constantlyurging the associated lever I@ to an elevated position. The motors 'iand the friction idlers il are so arranged that they are spacedcircumferentiaily around the turntable.

When the lever I9 is in the elevated position shown in Fig. 2, thefriction idlers 8 may be brought into engagement with the smallerdiameter portion la of the motor shaft and the periphery of theturntable to drive the turntable at a relatively slow speed, forexample, 331/3 R. P. M.; and when the lever i3 is depressed against theaction of the spring i2 to a point where the friction idler t is on thelevel of the larger diameter portion lb of the motor shaft, and thefriction wheel S is then brought into engagement with the shaft portion'ib and the turntable periphery, the turntable will be driven at arelatively higher speed, for example, '78 R. P. M. This particulardriving mechanism constitutes the subject matter of the above mentionedBrady and Weathers patent and is therein disclosed and claimed ingreater detail.

For adjustment of the levers I@ on their respective posts I l, weprovide a post I3 on a mot-or plate I4 which is carried by the motorboard I and, in turn, carries the motors and we slidably and rotatablymount a sleeve I5 on the post I3. The sleeve I5 is provided with abayonet slot IB through which a pin II on the post I3 extends, thesleeve I5 being also provided with a pair of oppositely extending armsI8 which are bifurcated at their ends to receive the upper ends of theposts I I and against which the springs I2 hold the upper ends of thecollars I9 formed on the levers I8. With the sleeve I5 in the positionshown in Fig. 2, wherein the pin Il is in the vertical portion 0i` thebayonet slot I6, the springs I2 are free to elevate the levers ID to aposition wherein the friction idlers 8 are in alignment with the smallerdiameter motor shaft portions 1a. On the other hand, by depressing thesleeve I5 on the post I3 until the horizontal portion of the bayonetslot IS engages the pin Il, the levers I8 are forced down against theaction of the springs I2 to bring the idler wheels 8 in alignment withthe larger diameter motor shaft portions IZL The sleeve I5 may be lockedin the latter position by simply turning it slightly in a clockwisedirection (looking down from the top) to cause the portion I 6a of thebayonet slot I 6 to embrace the pin I'I. A pair of coil springs 28 eachfixed at one end to the motor plate I and at its other end to adownwardly extending lug on the respective arms 9 constantly urges eachof the associated idlers into engagement with the motor shafts and theturntable.

To enable disconnecting the idler wheels 8 from their respective motorshafts and the turntable, a lever 2l is pivoted on the post I3 and hasfixed at its ends a pair of upstanding pins 22 received in slots formedin the ends of a pair of levers 23 and 23a, each pivotally mounted on aseparate one of the posts I I. The lever 23 is provided with anupstanding member 24 which is arranged to engage the associated leverI0, and the lever i3 is provided with a similar upstanding member 24awhich is arranged to engage its associated lever lil, the lever 23abeing also provided with an operating handle 25. By moving the handle 25in a counterclockwise direction, as viewed in Fig. 1, the lever 23amoves with it in a counterclockwise direction to bring its member 24ainto engagement with the associated lever I and cause the latter to movein a counterclockwise direction about the shaft II to force the frictionidler 8 out of engagement with the associated motor' shaft and theturntable against the action of the connected spring 20. At the sametime, counterclockwise movement of the lever 23a eiects clockwisemovement of the lever 2l on the post I3, and this, in turn, effectscounter-- clockwise movement of the lever 23 and the lefthand lever I0to bring its associated friction idler 8 out of engagement with theassociated motor shaft and the turntable. Once the idlers 8 have beenuncoupled from the respective motors and the turntable, the sleeve I5may be adjusted on the post I3 to bring the idlers to the level ofeither the motor shaft portion la or the motor shaft portion Ib in themanner heretofore described, after which the operating handle 25 ismoved in the opposite direction from that previously indicated whereuponthe reverse action from that heretofore described takes place and thesprings 20 pull their respective idlers 8 into engagement with the motorshafts and the turntable periphery.

Fixed to the motor board I in proximity to the turntable yli is abracket 26 which carries a spring blade 21 having a friction lining 28secured thereto. An arm 29 is adjustably mounted on the lever 23a andextends laterally from the lever 23a toward the spring blade 21, therebeing a suitable clearance between the spring 21 and the adjacent end ofthe arm 29. When'- the lever 23a is turned in a counterclockwisedirection, as viewed in Fig. l, to disconnect the idlers 8 from themotors 'l and the turntables 6, the right-hand end of the arm 29 willengage the free end of the blade 21 and press the brake lining againstthe turntable periphery to bring the turntable to a quick stop. This isvery desirable, in many instances, since the turntable is very massiveand would otherwise continue to rotate for a considerable period.

From the foregoing description, it will undoubtedly be apparent to thoseskilled in the art that we have provided an improved turntable drivewhich will insure a more constant or uniform drive for the turntablethan was attainable with drives heretofore employed. At the same time,the control mechanism for our improved drive is so arranged that theturntable is brought to a quick stop once the friction idlers aredisconnected therefrom.

Although we have shown and described but one embodiment of ourinvention, it will be apparent to those skilled in the art that manyother modifications thereof, as well as various changes in theparticular one described, are possible within the spirit of ourinvention. We, therefore, desire that our invention shall not be limitedexcept insofar as is made necessary by the prior art and by the spiritof the appended claims.

We claim as our invention:

1. In phonographic apparatus including a turntable, mechanism fordriving said turntable comprising a plurality of discrete drivingmembers, said members being spaced from each other circumferentiallyabout said turntable, a like plurality of friction idler wheels eachassociated with a separate one of said driving members, said idlerwheels being each movably mounted for movement into and out of powertransmitting position between their respective driving members and saidturntable, and control means common to all of said idler wheels forsimultaneously effecting movement of all said idler wheels into one orthe other of said positions.

2. In phonographic apparatus including a turntable, mechanism fordriving said turntable comprising a plurality of discrete motors, saidmotors being spaced from each other circumferentially about saidturntable, a like plurality of friction idler wheels each associatedwith a separate one of said motors, said idler wheels being each movablymounted for movement into and out of power transmitting position betweentheir respective motors and said turntable, and control means common toall of said idler wheels for simultaneously effecting movement of allsaid idler Wheels into one or the other of said positions.

3. In phonographic apparatus including a turntable, mechanism fordriving said turntable comprising a pair of motors spaced from eachother circumferentially about said turntable, each of said motors havinga shaft provided with driving portions of different diameters, a pair offriction idlers each associated with a separate one of said motors andmounted for movement into engagement with any preselected one of theirrespectively associated shaft portions `whereby to effect driving ofsaid turntable at any preselected one of a plurality of speeds, saididlers being also movably mounted for movement into engagement with saidturntable and said preselected shaft portions for transferring powerfrom'"their rspective motors to said turntable, and means including acommon control member for moving both said idlers simultaneously intoengagement with said turntable and the selected portions of their saidrespectively associated shaft portions at will.

4. In phonographic apparatus including a turntable, mechanism forcontrolling rotation of said turntable comprising a plurality ofdiscrete motors for driving said turntable, said motors being spacedfrom each other circumferentially about said turntable, a like pluralityof friction idler wheels each associated with a separate one of saidmotors, said idler wheels being each movably mounted for movement intoand out of power transmitting position between their respective motorsand said turntable, control means common to all of said idler wheels forsimultaneously effecting movement of all said idler wheels into one orthe other of said positions, a brake device associated with saidturntable, and means associated with said control means for applyingsaid brake device to said turntable when said f control means isoperated to eiect movement of said idler wheels out of said powertransmitting position.

5. In phonographic apparatus including a turntable, mechanism forcontrolling rotation of said turntable comprising a pair of motorsspaced from each other circumferentially about said turntable, each ofsaid motors having a shaft provided with driving portions of differentdiameters, a pair of friction idlers each associated with a separate oneof said motors and mounted for movement into engagement with anypreselected one of their respectively associated shaft portions wherebyto effect driving of said turntable at any preselected one of aplurality of speeds, said idlers being also movably mounted for movementinto engagement with said turntable and said preselected shaft portionsfor transferring power from their respective motors to said turntable,means including a common control member for moving both said idlerssimultaneously into engagement with said turntable and the selectedportions of their said respectively associated shaft portions at will, abrake device associated with said turntable, and means associated withsaid control member for applying said brake device to said turntablewhen said control member is operated to effect movement of said idlerwheels out of said power transmitting position.

JOHN J. HOEHN. ARTHUR G. ZIMMERMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 705,636 Birnbaum July 29, 19021,370,899 Molesworth Mar. 8, 1921 1,660,489 Hirvonen Feb. 28, 19281,874,550 Kuhn Aug. 30, 1932 2,097,071 Lichten Oct. 26, 1937 2,228,931Rysick Jan. 14, 1941 2,254,066 Gruber Aug. 26, 1941 2,260,289 Brady etal. Oct. 28, 1941 2,311,597 Schmitter Feb. 16, 1943 2,322,014 Grant June15, 1943 2,325,602 Gay Aug. 3, 1943

